EP2718187B1 - Device for reducing structural vibrations of aerofoils - Google Patents

Description

The invention relates to a wing with a device for reducing structural vibrations.

Turbulence in particular stimulates aircraft wings to vibrate, resulting in high dynamic loads and reduced passenger comfort. The damping or compensation of the wing bending vibrations by means of aerodynamic valves is for example off WO 2007-061641 . US 4,479,620 . DE 198 41 632 or EP 1 814 006 known. The fundamental vibration is relatively low frequency (about 1 Hz.) In the wings of large passenger and transport aircraft and depends on various circumstances, in particular the airspeed. Higher wing flex modes also affect passenger comfort and the range of the flaps is often insufficient to adequately cushion higher modes. In addition, a long-lasting dynamic operation of the valves leads to wear of the actuator and thus to increased maintenance. Another disadvantage is that the valve influence on the vibrations is Machzahl- and speed-dependent. On this basis, the present invention seeks to effect an effective damping of the structural vibrations in the wings without the arrangement of flaps to increase the life of the structure or to reduce the structural weight by lighter construction.

The publication US 2002/066831 A1 describes a wing tip member movably mounted on the exterior of a wing. It discloses the preamble of claim 1.

The publication WO 03/065142 A1 describes a damping device with a sensor and a vibration generator for generating damping vibrations.

The publication FR 2 825 769 A1 describes a device with an electric motor with a coil and a magnetic circuit which is attached to a spring.

The publication US 2005/093302 A1 describes a generator that converts vibration energy into electrical energy.

The publication US 2006/255206 A1 describes an aircraft with a system for suppressing lateral bends which is aerodynamically initialized during flight.

The publication DE 39 35 893 A1 describes a spring-mass system for damping dynamic instabilities of flows around structures.

According to the invention, this object is achieved in that at least one force generator acting essentially in the direction of vibration movement is provided in the region of the wing tips. This arrangement has the advantage that such a power generator is much less susceptible to wear than aerodynamic valves and thus effective vibration damping with reduced maintenance and higher efficiency is possible. Furthermore, power generators are effective, especially at higher frequencies. Under "vibration movement direction" is understood according to the vertical direction. So the direction of vibration of the wing, which is vertical in conventional horizontal wings but may slightly deviate from the vertical direction in upwardly inclined wings.

According to the invention, the force generators are each arranged in the wing winglet. These vertically extending surfaces at the ends of the wing to Improvement of the glide ratio provide a suitable space for power generators.

According to an advantageous embodiment of the invention, the natural frequency of the force generators is tuned to a selected vibration frequency of the wing, in particular the second symmetrical or antisymmetric wing bending vibration. Thus, this vibration can passively attenuate or simultaneously use for vibration damping and energy. No further energy supply is necessary for this, the system is completely self-sufficient.

According to an advantageous development of the invention, the natural frequency of the force generators is tuned to a mean oscillation frequency of the frequency range of interest. This not only a passive vibration damping for the identical excitation frequency can be achieved, but also for deviating excitation frequencies (typically ± 10%) is a vibration damping by force introduction in a suitable amplitude and phase possible. Outside this range, although the oscillation movement can not be completely minimized, however, a reduction of the oscillation movement can also be achieved here. Higher-harmonic movements can be realized by superimposing higher-harmonic force applications, but without taking advantage of the oscillation overshoot by the passive system.

According to an advantageous development of the invention, forces of suitable amplitude and phase at different selected frequencies are introduced into the wing structure for flutter damping in order to influence the critical flutter speed, for example by shifting one or more selected natural frequencies. According to an advantageous embodiment of the invention, each power generator is designed as a vertically oriented linear motor with movable primary or secondary part. This allows a structurally simple design of the power generator, wherein depending on the expediency of the primary or secondary part movable, so as a runner, may be formed. As a result, necessary components of the power generator are used simultaneously as a vibrating mass, thus keeping the system weight low.

Preferably, the force generator comprises a magnetic or magnetizable rotor, which is vertically oscillatable via at least one stationarily supported spring device and a guide and is surrounded by a stator coil. This training is structurally particularly simple and can be performed in any vertical length.

Preferably, the runner is supported stationary at both ends via a double-bar spring. This training allows for low construction costs at the same time a suspension and guidance of the rotor.

Preferably, the runner on a movement stroke of 20 to 60 cm. In this area, a relatively low rotor mass can be used to dampen the typical vibration frequencies in the range of approx. 1-6 Hz.

Preferably, the runner has a mass of 5 to 20 kg. In this range, an oscillation stroke suitable for placement in a winglet can be used to dampen the typical vibration frequencies in the range of approximately 1-6 Hz.

According to an advantageous embodiment of the invention, the power generator is switchable as a power generator, that is possible to generate electrical energy while damping the structural vibrations in the natural frequency range.

According to an advantageous embodiment of the invention, two or more force generators are provided with different natural frequencies per winglet. Thus, different vibration modes can be optimally damped, or a force generator tuned to the fundamental can operate as a current generator and the higher vibration modes are processed by the one or more force generators. The individual power generators can also be made structurally smaller.

According to one embodiment of the invention, the force generators comprise moving masses in the form of mobile fluids.

This embodiment allows not in accordance with the invention, the installation in wings without winglets and dispenses with the otherwise necessary installation of extra weights as a necessary component of the power generators. Rather, existing masses in the form of tanks, such as fuel tanks, used for this purpose.

According to a non-inventive development of this training, the fuel tanks are displaced in an oscillating motion. Thus, virtually no additional mass must be provided in the outer area of the wings.

According to an alternative embodiment of this embodiment not according to the invention, at least two volume-variable volume elements are arranged in the interior of the fuel tanks, which are arranged at the top or bottom in the fuel tank and have mutually offset by 180 ° oscillating variable volume. This design has the advantage that, apart from the bellows, there are no movable components which have to be stored or guided. By selecting the elastic properties of the bellows, and the choice of the system which inflates the bellows oscillating the resonance frequency of the bellows system is tuned to the natural frequency of the wing vibration to be controlled. By exploiting the resonant peaking of the bellows system, the energy required to inflate and deflate the bellows is minimized.

According to a non-inventive development of this embodiment, the resonant frequency of the volume-adjustable volume elements is tuned to the natural frequency of the wing vibration to be controlled. By exploiting the resonant peaking of the bellows system, the energy required to inflate and deflate the bellows is minimized.

According to a non-inventive embodiment of the invention, a closed cavity is oscillating in the fuel tank movable and whereby the fluid displaced and a shift in the center of gravity of the fluid is achieved.

Figur 1:

eine schematische perspektivische Darstellung eines Flugzeugs mit Winglets;

Figur 2:

eine Seitenansicht mit einem schematisch dargestellten Kraftgenerator;

Figur 3:

eine schematische Schnittdarstellung eines nicht erfindungsgemäßen Tragflügels mit einem Treibstofftank mit Blasebälgen;

Figur 4:

eine schematische Schnittdarstellung eines nicht erfindungsgemäßen Tragflügels mit einem oszillierbaren Treibstofftank;

Figur 5:

eine schematische Schnittdarstellung eines nicht erfindungsgemäßen Tragflügels mit einem oszillierbaren Treibstofftank mit bewegbarem Hohlraum.

The invention will be explained in more detail below with reference to a preferred embodiment with reference to the accompanying drawings. Showing:

FIG. 1:

a schematic perspective view of an aircraft with winglets;

FIG. 2:

a side view with a schematically illustrated power generator;

FIG. 3:

a schematic sectional view of a non-inventive wing with a fuel tank with bellows;

FIG. 4:

a schematic sectional view of a non-inventive wing with an oscillatable fuel tank;

FIG. 5:

a schematic sectional view of a non-inventive wing with an oscillatable fuel tank with movable cavity.

In FIG. 1 an aircraft 10 with fuselage 12, tail 14 and two wings 16 is shown, at the ends of each a substantially vertically aligned winglet 18 is arranged. In normal flight operations, but especially in turbulence, the wings 16 tend to oscillate in the directions denoted by 20 by the vibration axis 22 located in the region of the mounting of the wings 16 on the fuselage 12.

In FIG. 2 is a schematic side view of a winglet 18 shown, in which a force generator 24a is arranged. This force generator 24a consists essentially of a rotor 26 which is surrounded by a coil 28. At both ends 26 are mounted on the runner double beam springs 30 whose other ends are rigidly fixed to mounting stops 32, which in turn are supported on structural components of the winglet 18. In this way I can realize a bearingless motor, wherein the mounting stops 32 serve both as a stop for the rotor 26 and as a guide suspension for the entire power generator 24a. By the two double-bar springs 30 it is achieved that the rotor 26 is guided linearly. About the coil 28, the rotor 26 can either put in motion or hold. Alternatively, passively induced power can be derived by utilizing the moving field for power generation. The rotor 26 may either contain a permanent magnet, which simultaneously represents the moving mass or be designed as an electromagnet with an electrically connected coil.

A preferred embodiment of the force generator 24a according to the invention has a mass of the rotor 26 of 10 kg. With an excitation of 4000 N and an oscillation frequency of about 4.2 Hz, there is a deflection of the rotor 26 of about 56 cm. In this case, a frequency range of about +/- 10% with relatively small additional forces of about 700 N can be completely damped.

In operation, the vibration of the wing 16 is detected via sensors, not shown, and fed to a control device, which acts on the coil 28 via an electrical amplifier and controls so that the vibration reduction is maximum. Since current is generated out of phase by the oscillating movement of the rotor 26 in the field of the coil 28, the energy consumption of the force generator 24a is essentially limited to the electrical and mechanical losses and only slightly loads the vehicle electrical system. If the flight speed of the aircraft 10 is changed or the turbulence situation and thus the oscillation frequency of the wing oscillations, this can be taken into account by appropriate control of the coils 28.

FIG. 3 is a schematic sectional view through a wing 16 in the region of the wing tip with a non-inventive embodiment of a force generator 24b. Schematically illustrated is a fuel tank 34a, which remains constantly filled with fuel during operation and is only used up in exceptional or emergency situations. Its contents, the fuel or the filled fuel tank 34a itself can be used for the power generator. In the in FIG. 3 illustrated embodiment, two bellows 36, 38 are arranged in the interior of the fuel tank 34a above and below, which can be filled alternatively via air pressure lines, not shown are. Each having the reference numerals (a), ie 36a, 38a, a first position is shown, in which the upper bellows 36a filled and the lower bellows 38a is empty, so that the center of gravity of the fluid in the fuel tank 34a below the geometric center of the fuel tank 34a lies. Each reference numeral (b), ie 36b, 38b, a second position is shown, in which the upper bellows 36a is empty and the lower bellows 38a is filled, so that the center of gravity of the fluid in the fuel tank 34a is above the geometric center of the fuel tank 34a , Between these two end positions, an oscillation process takes place, which causes the fluid in the fuel tank 34a to oscillate vertically and in this way forms a force generator 24b.

FIG. 4 is like FIG. 3 a schematic sectional view of an airfoil 16 in the region of the wing tip with a fuel tank 34b for fuel, which is oscillatory by means of an oscillating device 40 in a direction perpendicular to the wing longitudinal axis and thus forms the non-inventive force generator 24c.

FIG. 5 is like FIGS. 3 and 4 a schematic sectional view of an airfoil 16 in the region of the wing tip with a fuel tank 34c for fuel with another non-inventive embodiment of a force generator 24d. The fuel tank 34c itself is fixed but contains inside a fluid-free hollow body 42 which is oscillating over a number of actuators 44 (electromechanical, pneumatic or hydraulic) oscillating. As a result, fuel is displaced and causes a shift in the center of gravity of the fluid.

LIST OF REFERENCE NUMBERS

10

plane

12

hull

14

tail

16

Hydrofoil

18

winglet

20

vibration direction

22

axis of oscillation

24a-d

power generator

26

runner

28

Kitchen sink

30

Double beam springs

32

fastening stopper

34a, b

fuel tank

36a, b

bellows

38a, b

bellows

40

oscillation

42

hollow body

44

actuators

Claims (11)

1. Wing (16) for an aircraft having a device which is provided on the wing tip and intended for reducing structural vibrations by an oscillating body, characterized in that a winglet (18) having a force generator (24) integrated therein which acts in the vertical direction is arranged on the wing tip.
2. Wing (16) according to Claim 1, characterized in that the natural frequency of the force generator (24) is tuned to the first or second symmetrical or antisymmetrical flexural wing vibration.
3. Wing (16) according to Claim 1, characterized in that the natural frequency of the force generator is tuned to an average vibration frequency of the relevant frequency range.
4. Wing (16) according to Claim 1, characterized in that each force generator (24) is designed as a vertically oriented linear motor having a movable primary or secondary part (26).
5. Wing (16) according to Claim 4, characterized in that the force generator (24a) comprises a magnetic or magnetizable rotor (26) which is capable of oscillating vertically via at least one spring device (30), which is supported in a positionally fixed manner, and a guide (30) and is surrounded by a stator coil (28).
6. Wing (16) according to Claim 4, characterized in that the force generator comprises an oscillateable coil and a magnetizable stator.
7. Wing (16) according to Claim 5, characterized in that the rotor (26) is supported in a positionally fixed manner at both ends with a respective double beam spring (30).
8. Wing (16) according to one of the preceding claims, characterized in that the force generator (24) can be switched as a current generator.
9. Wing (16) according to Claim 1, characterized in that two or more force generators (24) having different natural frequencies are provided for each winglet (18).
10. Wing (16) according to one of Claims 1 to 3, characterized in that the force generator (24) comprises moving masses in the form of movable fluids.
11. Aeroplane (10) having a wing (16) according to at least one of the preceding claims.

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